1. Field of the Invention
The invention is in the field of electronic pipetters. In particular, the invention relates to a method for programming an electronic pipetter.
2. Description of Related Art
A conventional mechanical pipet is usually a small piece of apparatus with which fluids are transferred, measured, absorbed, etc., as in chemical operations. The simplest form is a narrow glass tube, such as an eyedropper, the liquid being drawn up into it by suction (aspiration) and retained by closing the upper end. The liquid can then be dispensed in measured, equal fractional amounts, called aliquots. For example, if the pipet contains 25 ml of liquid, 8 aliquots of 3 ml of liquid can be dispensed, with 1 ml of liquid left over.
More recently, a computer-controlled electronic pipetter has been developed to aspirate and dispense various liquid media through an attached pipette. This computer-controlled electronic pipetter has a user interface consisting of a liquid crystal display (LCD) and programming keys. However, the methodology for programming this pipetter is difficult to use, because the order of programming commands is neither intuitive nor easy to remember, and the displayed aspirating and dispensing parameters required to be set or selected in any given programming step are often difficult to understand or ambiguous. This forces the users to rely extensively on product manuals to learn and relearn the correct programming methodology, especially when the user has not used the existing electronic pipetter in weeks or months. Moreover, because there is no intuitive programming methodology with respect to the complexity of the desired operational mode in the existing electronic pipetter, new users are often intimidated by the immediate complex programming requirements when first turning on the existing electronic pipetter, discouraging their further use of such a pipetter. In addition, the existing electronic pipetter does not provide the user with a simple, single-parameter "quick-shot" programming mode or a multiple aspiration-dispensation "hands-free" operating mode.
The information displayed on the LCD of the existing electronic pipetter is generally limited to single letters or initials to indicate, in a non-intuitive fashion, the operational modes and status of the pipetter. Moreover, this LCD can only display a limited number of characters, each corresponding to several control functions, thus creating ambiguities. The functions can only be displayed one at a time, making selection of any one function difficult. For example, the same characters are used to display the selected operating mode and to display the selected number of aliquots to be dispensed. When one of those two parameters is displayed, the other is not. If the user wishes to examine or reset the other non-displayed parameter, the user must switch between the displays, which is not only inconvenient, but is often difficult since the user's fingers are usually otherwise occupied conducting the pipetting operation. Further, the LCD of the existing pipetter simply does not offer any guidance on which programming step comes next when a sequence of steps must be entered.
In summary, because of the above-described programming and display limitations in the existing electronic pipetter, measurement and dispensing precision suffers, causing variability between the aliquots of dispensed liquid. Therefore, despite the current availability of an electronic pipetter with an LCD and keys for programming, there is still a need for a more user-friendly, easy-to-program electronic pipetter. In particular, there is a need for an electronic pipetter having an advanced programming methodology and an easy-to-understand display so that the user can more exactly and quickly control the electronic pipetter, which in turn provides more precise, repeatable measuring and dispensing of fluids. An improved electronic pipetter is especially needed by those users who prepare large numbers of tissue cultures, in which aliquot precision and repeatability is absolutely demanded.